{"id":"CVE-2026-33693","state":"PUBLISHED","title":"Lemmy's Activitypub-Federation has SSRF via 0.0.0.0 bypass in activitypub-federation-rust v4_is_invalid()","description":"Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.7.0-beta.9, the `v4_is_invalid()` function in `activitypub-federation-rust` (`src/utils.rs`) does not check for `Ipv4Addr::UNSPECIFIED` (0.0.0.0). An unauthenticated attacker controlling a remote domain can point it to 0.0.0.0, bypass the SSRF protection introduced by the fix for CVE-2025-25194 (GHSA-7723-35v7-qcxw), and reach localhost services on the target server. Version 0.7.0-beta.9 patches the issue.","publishedAt":"2026-03-27T00:03:35.946Z","updatedAt":"2026-03-30T11:51:10.425Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["LemmyNet lemmy"],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.7.0-beta.9","status":"affected"}]}],"references":["https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35","https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599","https://github.com/advisories/GHSA-7723-35v7-qcxw"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33693.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33693","state":"PUBLISHED","datePublished":"2026-03-27T00:03:35.946Z","dateUpdated":"2026-03-30T11:51:10.425Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-23T16:34:59.932Z"},"containers":{"cna":{"title":"Lemmy's Activitypub-Federation has SSRF via 0.0.0.0 bypass in activitypub-federation-rust v4_is_invalid()","descriptions":[{"lang":"en","value":"Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.7.0-beta.9, the `v4_is_invalid()` function in `activitypub-federation-rust` (`src/utils.rs`) does not check for `Ipv4Addr::UNSPECIFIED` (0.0.0.0). An unauthenticated attacker controlling a remote domain can point it to 0.0.0.0, bypass the SSRF protection introduced by the fix for CVE-2025-25194 (GHSA-7723-35v7-qcxw), and reach localhost services on the target server. Version 0.7.0-beta.9 patches the issue."}],"affected":[{"vendor":"LemmyNet","product":"lemmy","versions":[{"version":"< 0.7.0-beta.9","status":"affected"}]}],"references":[{"url":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35","name":"https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599","name":"https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599","tags":["x_refsource_MISC"]},{"url":"https://github.com/advisories/GHSA-7723-35v7-qcxw","name":"https://github.com/advisories/GHSA-7723-35v7-qcxw","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-27T00:03:35.946Z"},"source":{"advisory":"GHSA-q537-8fr5-cw35","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-30T11:50:59.456186Z","id":"CVE-2026-33693","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-30T11:51:10.425Z"}}]}}}